Sheath and potential characteristics in rf magnetron sputtering plasma

Abstract

Using an emissive probe with an additional compensating electrode, the axial and radial variations of potential are determined in a rf planar magnetron discharge at constant argon flow. The axial potential structure shows the sheath formation near the powered electrode (cathode). In the cathode sheath, the high potential drop in the racetrack region indicates the existence of a strong electric field required for effective sputtering. Results reveal that the potential structure along a line parallel to the surface of the powered electrode exhibits radial variations. Dependence of potential structure in the cathode sheath due to the negative dc self-bias at different applied rf powers has also been observed. The ion density and the electron temperature are measured at different axial and radial positions with the help of a compensating Langmuir probe to correlate with the results found from emissive probe measurements.